Thor-Odin dome: constraints on paleocene-eocene anatexis and deformation, leucogranite generation and the tectonic evolution of the southern Omineca Belt, Canadian Cordillera

Hinchey, Alana M.

doi:10.22215/etd/2005-06698

Cited by 5 publications

(18 citation statements)

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“…We interpret focused deformation on the Monashee ramp (Hinchey 2005;Gervais 2009) and the successive stacking of thrust sheets and ductile infrastructure in the orogenic core (Simony and Carr, in preparation) as the product of underthrust indentation in an analogous way to the inferred behaviour of the basement beneath the western Grenville Orogen (models GRL1a to GRL1 shown with reversed polarity in Fig. 9).…”

Section: Application Of Model Results To the Southern Canadian Cordilmentioning

confidence: 82%

“…9. Variations of model GRL1 (shown reversed) with different syn-orogenic erosion rates (parts (c), (e), and (g)) shown compared with interpreted cross section of the southern Canadian Cordillera: (a) modified from Cook (1995b), (b) modified from Hinchey (2005), (d) and (f) modified from Carr and Simony (2006). Note the models are shown in a configuration corresponding to the end of orogenesis and do not include the effects of postorogenic erosion and isostatic rebound.…”

Section: Application Of Model Results To the Southern Canadian Cordilmentioning

confidence: 99%

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Models of large, hot orogens containing a collage of reworked and accreted terranesThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.

2010

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We describe a classification scheme for orogens using Temperature-Magnitude (T-M) diagrams and use this framework for modelling large, hot orogens that evolve in continents comprising cratonic nuclei bordered by a series of juvenile accreted, reworked, and metamorphosed terranes. Modelling the complete evolution of an orogen is difficult, particularly large orogens with multiple orogenic phases. Early phases during which a continent is assembled produce a tectonic and metamorphic fabric that needs to be taken into account when modelling the main collisional orogeny. This inherited fabric is represented in a simple way in models described here by a series of lower crustal blocks that are arranged to be systematically stronger toward the cratonic continental interiors. We investigate how this fabric influences the development of the model orogen during the main collisional phase using upper-mantle-scale (UMS) and crustal-scale (CS) finite element models. The models exhibit a diachronous three-phase evolution: crustal thickening, thermal incubation, and lower crustal indentation. The UMS and CS models are shown to give comparable results in regard to crustal deformation. The UMS models exhibit additional features including single-and double-slab breakoffs and corresponding episodes of uplift and gravitational spreading within the orogenic crust. Protracted postconvergent gravitational spreading of the hot, decoupled crust is also demonstrated. Lastly, we demonstrate the application of this type of model to natural orogens, the Grenville orogen in western Ontario and the southern Canadian Cordillera, and in terms of the T-M diagram.Résumé : Le présent article décrit un système de classification des orogènes basé sur des diagrammes température-magnitude et nous utilisons ce cadre pour modéliser de gros orogènes chauds qui ont évolué dans les continents qui comportaient des noyaux de cratons délimités par une série de terranes juvéniles, accrétés, retravaillés et métamorphosés. Il est difficile de modéliser l'évolution complète d'un orogène, surtout les gros orogènes comportant de multiples phases orogéniques. Les premières phases durant lesquelles un continent est assemblé produisent une fabrique tectonique et métamorphique dont il faut tenir compte lors de la modélisation de l'orogène principale de collision. Cette fabrique héritée est représentée d'une manière simple dans les modèles décrits ici par une série de blocs dans la croûte inférieure qui sont arrangés pour être systématiquement plus forts vers l'intérieur des cratons continentaux. Nous étudions comment cette fabrique influence le développement de l'orogène modèle au cours de la principale phase de collision en utilisant des modèles aux éléments finis à l'échelle du manteau supérieur et à l'échelle de la croûte. Les modèles présentent une évolution en trois phases diachroniques, un épaississement de la croûte, une incubation thermique et une indentation de la croûte inférieure. Les modè-les à l'échelle du manteau supérieur et à l'échelle de la croûte donnen...

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Section: Application Of Model Results To the Southern Canadian Cordilmentioning

confidence: 82%

Section: Application Of Model Results To the Southern Canadian Cordilmentioning

confidence: 99%

Models of large, hot orogens containing a collage of reworked and accreted terranesThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.

2010

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“…Duration of protracted greenschist facies deformation along the Columbia River detachment [49.0 to 47.9 Ma, Vanderhaeghe et al , 2003; Mulch et al , 2004, 2006b] covers almost the entire range of muscovite cooling and recrystallization ages in the various core complex‐bounding detachments (∼50 to 45 Ma). A case has been made that the timing of decompression melting in the middle crust due to exhumation is recorded in ∼56 to 52 Ma zircon rims of anatectic migmatite in the Shuswap metamorphic core complex [ Vanderhaeghe et al , 1999; Hinchey , 2005]. An emerging body of SHRIMP U‐Pb zircon data now documents the widespread occurrence of 52–57 Ma zircon growth associated with midcrustal flow in several Eocene core complexes [ Foster and Fanning , 1997; Vanderhaeghe et al , 1999; Foster et al , 2001; Foster et al , 2007].…”

Section: Geological Setting and Age Constraintsmentioning

confidence: 99%

Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera

Mulch¹,

Teyssier²,

Cosca

et al. 2007

Tectonics

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The hydrogen isotope composition of Eocene muscovite in mylonitic quartzite from the Kettle and Shuswap metamorphic core complexes (Washington and British Columbia) permits estimates of paleoaltimetry of the North American Cordillera at the onset of post‐collisional lithospheric extension. Coupled oxygen, hydrogen, and 40Ar/39Ar isotope data indicate that meteoric water penetrated to significant depths during normal faulting along the Columbia River Detachment bounding both Kettle and Shuswap metamorphic core complexes. Synkinematic muscovite attains δDmuscovite values as low as −135‰ and −157‰, respectively, consistent with δDwater values of −115 ± 5‰ and −135 ± 5‰. In context with stable isotope data from Eocene sedimentary basins of continental North America, these data constrain the isotopic composition of precipitation from which paleoelevation estimates can be made. Stable isotope paleoaltimetry indicates that during detachment formation (49–47 Ma), orogen‐parallel variations in topography existed, and mean elevations decreased from ≥4000 m at the latitude of the Shuswap core complex to ≥3000 m in the Kettle core complex. In addition, these data indicate a net decrease in mean surface elevation by ∼1000 m since the Eocene. Our results for the Kettle core complex are consistent with paleoelevation estimates based on fossil floral physiognomy in the Eocene Republic basin (Washington), indicating that high elevations characterized not only the frontal escarpment near the crustal‐scale detachment but continued into the Okanogan highlands further west. Collectively, the stable isotope, geochronological, and paleofloral data support tectonic models of high Eocene surface elevations contemporaneous with magmatism and lithospheric extension.

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“…In some regions, such as the NW corner of Figure 1, infrastructure was reactivated and was hot and mobile in the Early Cretaceous only (Scammell 1993;Parrish 1995, and references therein;Simony & Carr 1997;Digel et al 1998). In some regions, such as the area east, west and NW of Frenchman Cap dome (Scammell 1993;Brown & Gibson 2006, and references therein), the infrastructure was hot and mobile in the Early and Late Cretaceous, while elsewhere, such as in the Thor Odin and Valhalla domes, only Late Cretaceous (Spear & Parrish 1996;Johnston et al 2000) or Palaeogene (Hinchey 2005) ages have been obtained. Locally, however, in the NW corner of Figure 1, and perhaps in the southern part of the Valhalla complex (Figs 1 & 4), a transition zone is preserved from the Jurassic suprastructure to a Jurassic infrastructure with recumbent folds and gently dipping foliation (Pell & Simony 1982;Murphy 1987;Digel et al 1998).…”

Section: Three Crustal Zones and The Suprastructure-infrastructure Asmentioning

confidence: 99%

“…The infrastructural gneissic sheet is at its thickest (15-20km;Johnston et al 2000) and perhaps hottest (Norlander et al 2002) in the Thor Odin dome (Hinchey 2005;Hinchey et al 2006). It is of interest that it is NE of this thick, hot, central zone that the Late Cretaceous-Palaeocene thrusts of the Rocky Mountain Front Ranges have their greatest displacement.…”

Section: Northward Continuation Of the Gwillim Creek Shear Zonementioning

confidence: 99%

Ductile thrusting versus channel flow in the southeastern Canadian Cordillera: evolution of a coherent crystalline thrust sheet

Carr

Simony

2006

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The Late Cretaceous Gwillim Creek shear zone (GCSZ) exposed in the core of the Valhalla complex, and located in the hinterland of the southern Canadian Rocky Mountain thrust belt, is a 5-7 km thick, easterly verging, ductile thrust zone. It was active after c. 90 Ma and during anatexis (800~ and 800 MPa), rose eastward in the direction of transport, and its base was refrigerated from below at c. 60 Ma by thrust translation onto a cold footwall. Extensional shear zones are younger than the GCSZ, and there is no evidence of channel flow or ductile extrusion. Instead, a 30 km thick, coherent sheet was translated on the GCSZ, which at depth was linked to the Foreland thrust belt such as to form a composite crystalline thrust sheet. Doming of the Valhalla complex may be related to Eocene thrusting beneath the complex during the last stage of shortening. A channel flow, proposed by others for the region north of the Valhalla complex, could have evolved within the crystalline sheet by activation of lateral transition zones and an upper detachment, but is no wider than 250 km, does not represent the dominant orogenic process and may represent a nascent channel.

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Thor-Odin dome: constraints on paleocene-eocene anatexis and deformation, leucogranite generation and the tectonic evolution of the southern Omineca Belt, Canadian Cordillera

Cited by 5 publications

References 0 publications

Models of large, hot orogens containing a collage of reworked and accreted terranesThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.

Models of large, hot orogens containing a collage of reworked and accreted terranesThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.

Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera

Ductile thrusting versus channel flow in the southeastern Canadian Cordillera: evolution of a coherent crystalline thrust sheet

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